Transparent thermoplastic resin and method of preparing the same

ABSTRACT

The present disclosure relates to a thermoplastic resin having excellent non-whitening properties, impact strength, gloss, and fluidity, and a method of preparing the thermoplastic resin. The thermoplastic resin includes an alkyl acrylate-alkyl methacrylate graft copolymer (A), or the copolymer (A) and a matrix resin (B) including an alkyl methacrylate polymer and/or an alkyl methacrylate-alkyl acrylate copolymer. A transparency of the thermoplastic resin having a thickness of 0.15 mm is less than 2, a total content of the alkyl acrylate in the thermoplastic resin is 20 to 50% by weight, and a butyl acrylate coverage value (X) as calculated by Equation 1 below is 50 or more:X={(G−Y)/Y}×100,  [Equation 1]wherein G represents a total gel content (%) of the thermoplastic resin, and Y represents a content (% by weight) of butyl acrylate in the gel of the thermoplastic resin.

TECHNICAL FIELD Cross-Reference to Related Applications

This application claims priority to Korean Patent Application No.10-2020-0100369, filed on Aug. 11, 2020, and Korean Patent ApplicationNo. 10-2021-0091422, re-filed on Jul. 13, 2021, based on the priority ofthe above patent, in the Korean Intellectual Property Office, thedisclosures of each of which are incorporated herein by reference.

The present invention relates to a transparent thermoplastic resin. Moreparticularly, the present invention relates to a transparentthermoplastic resin having excellent transparency, impact strength,gloss, fluidity, and weather resistance and excellent non-whiteningproperties, characterized in that whitening does not occur when bent orhit, and a method of preparing the thermoplastic resin.

BACKGROUND ART

Acrylonitrile-butadiene-styrene resins (hereinafter referred to as “ABSresins”) based on conjugated diene rubber have excellent processability,mechanical properties, and appearance properties, and thus have beenwidely used in electric and electronic products, automobiles, smalltoys, furniture, construction materials, and the like. However, sinceABS resins are based on butadiene rubber containing an unsaturated bondthat is chemically unstable, ABS resins have very poor weatherresistance due to aging of the rubber polymer by ultraviolet light.Thus, ABS resins are not suitable as outdoor materials. To address suchproblems, a method of using ABS resins after painting has been proposed,but there is a problem of environmental pollution during the paintingprocess. In addition, the painted product is difficult to recycle andhas poor durability.

To overcome these problems of ABS resins, acrylic copolymers typified byacrylate-styrene-acrylonitrile graft copolymers (hereinafter referred toas “ASA resins”) without an ethylenically unsaturated bond have beenused. ASA resins have excellent physical properties, such asprocessability, impact resistance, chemical resistance, and weatherresistance, and thus have been used in various fields, such as materialsfor buildings, interior and exterior materials for automobiles andmotorcycles, electric and electronic products, ships, leisure goods, andgardening goods. In addition, there is increasing demand for ASA resins.However, appearance characteristics, such as colorability, of ASA resinsare poor, compared to painted ABS resins, and ASA resins areinsufficient to satisfy increasing weather resistance levels required inthe market.

In addition, as the importance of aesthetics increases in the market,research is being conducted to realize a luxurious appearance andexcellent colorability and weather resistance by finishing the outersurfaces of substrates, such as ABS, PVC, and steel sheets, withthermoplastic resins. Such a finishing material is mainly manufacturedin the form of a film and then processed into a final product through aprocess such as bending or folding according to the shape of a substrateto which the finishing material is applied. However, due to thecharacteristics of a thermoplastic ASA resin, when the above-describedfinishing treatment is performed at room temperature, whitening occurs,thereby losing the original color of the resin and deterioratingaesthetics.

Such a whitening phenomenon is analyzed to be caused by voids due tocracks occurring inside a thermoplastic resin when bent. To addressthis, a method for improving whitening properties by adjusting thecontent of rubber in a thermoplastic resin or by mixing a thermoplasticresin with an elastomer to soften a thermoplastic resin has beenproposed. However, the methods can address whitening, but there is aproblem that other mechanical properties, colorability, surface gloss,etc. are deteriorated. Accordingly, a thermoplastic resin compositionexhibiting excellent physical properties has not yet been developed, andnon-whitening properties have also not been satisfactorily implemented.

Related Art Documents Patent Documents

-   JP 1995-033470 B2

DISCLOSURE Technical Problem

Therefore, the present invention has been made in view of the aboveproblems, and it is one object of the present invention to provide atransparent thermoplastic resin having excellent transparency, impactstrength, gloss, weather resistance, and fluidity and excellentnon-whitening properties, characterized in that occurrence of whiteningis suppressed even when bent or hit and a method of preparing thethermoplastic resin. It is another object of the present invention toprovide a molded article manufactured using the thermoplastic resin ofthe present invention.

The above and other objects can be accomplished by the present inventiondescribed below.

Technical Solution

In accordance with an aspect of the present invention, the above andother objects can be accomplished by the provision of a thermoplasticresin, including: an alkyl acrylate-alkyl methacrylate graft copolymer(A), or an alkyl acrylate-alkyl methacrylate graft copolymer (A); and amatrix resin (B) including one or more selected from the groupconsisting of an alkyl methacrylate polymer and an alkylmethacrylate-alkyl acrylate copolymer, wherein a transparency (hazevalue), measured according to ASTM D-1003 under a condition of 0.15 mmthickness, is 2 or less, and a transparency measured under a conditionof 3 mm thickness is 4 or less, a total content of the alkyl acrylate is20 to 50% by weight, and a butyl acrylate coverage value (X) ascalculated by Equation 1 below is 50 or more:

X={(G−Y)/Y}×100,  [Equation 1]

wherein G represents a total gel content (%) of the thermoplastic resin,and Y represents a content (% by weight) of butyl acrylate in the gel ofthe thermoplastic resin.

In accordance with another aspect of the present invention, there isprovided a thermoplastic resin, including: an alkyl acrylate-alkylmethacrylate graft copolymer (A), or an alkyl acrylate-alkylmethacrylate graft copolymer (A); and a matrix resin (B) including oneor more selected from the group consisting of an alkyl methacrylatepolymer and an alkyl methacrylate-alkyl acrylate copolymer, wherein atransparency (haze value), measured according to ASTM D-1003 under acondition of 0.15 mm thickness, is 2 or less, and a transparencymeasured under a condition of 3 mm thickness is 4 or less, a totalcontent of the alkyl acrylate is 20 to 50% by weight, and a refractiveindex difference (according to ASTM D542) between a sol and a gel of thethermoplastic resin under a condition of using acetone is 0.02 or less.

In accordance with another aspect of the present invention, there isprovided a thermoplastic resin, including: an alkyl acrylate-alkylmethacrylate graft copolymer (A), or an alkyl acrylate-alkylmethacrylate graft copolymer (A); and a matrix resin (B) including oneor more selected from the group consisting of an alkyl methacrylatepolymer and an alkyl methacrylate-alkyl acrylate copolymer, wherein atransparency (haze value), measured according to ASTM D-1003 under acondition of 0.15 mm thickness, is 2 or less, and a transparencymeasured under a condition of 3 mm thickness is 4 or less, a totalcontent of the alkyl acrylate is 20 to 50% by weight, and an elutionamount of butyl acrylate in acetone is 0.01% by weight or more.

Preferably, a refractive index difference (according to ASTM D542)between a sol and a gel of the thermoplastic resin under a condition ofusing acetone may be 0.02 or less.

Preferably, the thermoplastic resin may include 50 to 100% by weight ofthe alkyl acrylate-alkyl methacrylate graft copolymer (A), and 0 to 50%by weight of the matrix resin (B) including one or more selected fromthe group consisting of an alkyl methacrylate polymer and an alkylmethacrylate-alkyl acrylate copolymer.

Preferably, when elution of the thermoplastic resin is performed usingacetone, an elution amount of butyl acrylate may be 0.01% by weight ormore.

Preferably, the copolymer (A) may include 25 to 50% by weight of analkyl acrylate rubber (a-1) having a DLS average particle diameter of 40to 120 nm or a TEM average particle diameter of 25 to 100 nm; and 50 to75% by weight of an alkyl acrylate-alkyl methacrylate copolymer (a-2)based on 100% by weight in total of the copolymer (A).

Preferably, the copolymer (A) may have a grafting degree of 60 to 200%,and the copolymer (a-2) may have a weight-average molecular weight of40,000 to 120,000 g/mol.

Preferably, the thermoplastic resin, the rubber (a-1), or both thethermoplastic resin and the rubber (a-1) may have a glass transitiontemperature of −50 to −20° C.

Preferably, the rubber (a-1) may further include alkyl methacrylate. Inthis case, the alkyl methacrylate may be included in an amount of 0.1 to25% by weight based on 100% by weight in total of the rubber (a-1).

Preferably, the copolymer (a-2) may include 80 to 99.9% by weight ofalkyl methacrylate and 0.1 to 20% by weight of alkyl acrylate based on100% by weight in total of the copolymer (a-2).

Preferably, a refractive index difference (according to ASTM D542)between the rubber (a-1) and the matrix resin (B) may be 0.02 or more.

Preferably, when the thermoplastic resin is extruded to obtain a filmhaving a thickness of 0.15 mm, and a weight having a weight of 1 kg isvertically dropped onto the film from a height of 100 mm at atemperature of 23° C. using a Gardner impact tester, a difference inhaze values measured before and after impact according to ASTM D1003-95for an area impacted (hit) by the weight may be 10 or less.

In accordance with another aspect of the present invention, there isprovided a method of preparing a thermoplastic resin, the methodincluding: a step of kneading and extruding an alkyl acrylate-alkylmethacrylate graft copolymer (A), or an alkyl acrylate-alkylmethacrylate graft copolymer (A); and a matrix resin (B) including oneor more selected from the group consisting of an alkyl methacrylatepolymer and an alkyl methacrylate-alkyl acrylate copolymer, wherein atransparency (haze value), measured according to ASTM D-1003 under acondition of 0.15 mm thickness, of the thermoplastic resin is 2 or less,and a transparency under a condition of 3 mm thickness is 4 or less, atotal content of the alkyl acrylate in the thermoplastic resin is 20 to50% by weight, and a butyl acrylate coverage value (X), as calculated byEquation 1 below, of the thermoplastic resin is 50 or more:

X={(G−Y)/Y}×100,  [Equation 1]

wherein G represents a total gel content (%) of the thermoplastic resin,and Y represents a content (% by weight) of the butyl acrylate in thegel of the thermoplastic resin.

Preferably, the graft copolymer (A) may be prepared by a methodincluding a step of emulsion polymerization of 100 parts by weight intotal of a monomer mixture including 25 to 50% by weight of alkylacrylate rubber having a DLS average particle diameter of 40 to 120 nmor a TEM average particle diameter of 25 to 100 nm; and 50 to 75% byweight of an alkyl acrylate compound and an alkyl methacrylate compound.

In accordance with yet another aspect of the present invention, there isprovided a molded article including the thermoplastic resin.

Preferably, the molded article may be a finishing material.

Advantageous Effects

As apparent from the foregoing, the present invention advantageouslyprovides a thermoplastic resin having excellent transparency, impactstrength, weather resistance, gloss, and fluidity and excellentnon-whitening properties, characterized in that whitening does not occureven when bent or hit and a method of preparing the thermoplastic resin.According to the present invention, the properties of the thermoplasticresin can be implemented by adjusting the particle diameter and contentof a rubber included in the resin, a grafting degree and molecularweight, a gel content of the resin, a refractive index differencebetween a sol and gel of the resin, and the like.

DESCRIPTION OF DRAWINGS

FIG. 1 includes images taken after bending, in the Md and Td directions,films manufactured in an example (left image) and a comparative example(right image) to check whether whitening occurs.

FIG. 2 includes images taken after hitting, using a Gardner impacttester, films manufactured in an example (left image) and a comparativeexample (right image) to check whether whitening occurs.

BEST MODE

Hereinafter, a thermoplastic resin of the present invention will bedescribed in detail.

The present inventors conducted studies to develop a transparentthermoplastic resin capable of providing a finishing material having aluxurious appearance. As a result of such study, the present inventorsconfirmed that transparency is improved by adjusting a refractive indexdifference between a sol and a gel, and non-whitening properties aresignificantly improved when formation of voids due to cracks isminimized by reducing the distance between rubber particles andincreasing a grafting degree up to a predetermined range. Based on theseresults, the present inventors conducted further studies to complete thepresent invention.

In this description, a resin does not mean only a single (co)polymer,and may include two or more (co)polymers as main components.

In this description, the composition ratio of a (co)polymer may mean thecontent of units constituting the (co)polymer, or may mean the contentof units fed during polymerization of the (co)polymer.

The thermoplastic resin of the present invention may include an alkylacrylate-alkyl methacrylate graft copolymer (A), or an alkylacrylate-alkyl methacrylate graft copolymer (A); and a matrix resin (B)including one or more selected from the group consisting of an alkylmethacrylate polymer and an alkyl methacrylate-alkyl acrylate copolymer,wherein a transparency measured according to ASTM D-1003 under acondition of 0.15 mm thickness is 2 or less, a transparency measuredunder a condition of 3 mm thickness is 4 or less, a total content of thealkyl acrylate is 20 to 50% by weight, and a butyl acrylate coveragevalue (X) as calculated by Equation 1 below is 50 or more. In this case,transparency, impact resistance, weather resistance, and moldingprocessability are excellent. In addition, whitening does not occur whenbent or hit. That is, non-whitening properties are excellent.

X={(G−Y)/Y}×100  [Equation 1]

In Equation 1, G represents the total gel content (%) of thethermoplastic resin, and Y represents the content (% by weight) of butylacrylate in the gel of the thermoplastic resin.

As another example, the thermoplastic resin of the present invention mayinclude 50 to 100% by weight of an alkyl acrylate-alkyl methacrylategraft copolymer (A); and 0 to 50% by weight of a matrix resin (B)including one or more selected from the group consisting of an alkylmethacrylate polymer and an alkyl methacrylate-alkyl acrylate copolymer,wherein a transparency (haze value) measured according to ASTM D-1003under a condition of 0.15 mm thickness is 2 or less, a transparencymeasured under a condition of 3 mm thickness is 4 or less, and value Xas calculated by Equation 1 below is 50% or more. In this case,transparency, impact resistance, weather resistance, and moldingprocessability are excellent. In addition, whitening does not occur whenbent. That is, non-whitening properties are excellent.

X (%)={(G−Y)/Y}×100  [Equation 1]

In Equation 1, G represents the total gel content (%) of thethermoplastic resin, and Y represents the content (% by weight) of butylacrylate in the gel of the thermoplastic resin.

In addition, as still another example, the thermoplastic resin of thepresent invention may include 50 to 100% by weight of an alkylacrylate-alkyl methacrylate graft copolymer (A); and 0 to 50% by weightof a matrix resin (B) including one or more selected from the groupconsisting of an alkyl methacrylate polymer and an alkylmethacrylate-alkyl acrylate copolymer, wherein the total content ofalkyl acrylate is 20 to 50% by weight, a transparency (haze value)measured according to ASTM D-1003 under a condition of 0.15 mm thicknessis 2 or less, a transparency measured under a condition of 3 mmthickness is 4 or less, and a refractive index difference (according toASTM D542) between a sol and a gel under a condition of using acetone is0.02 or less. In this case, transparency, impact resistance, weatherresistance, and molding processability are excellent. In addition,whitening does not occur when bent. That is, non-whitening propertiesare excellent.

In addition, as still another example, the thermoplastic resin of thepresent invention may include 50 to 100% by weight of an alkylacrylate-alkyl methacrylate graft copolymer (A); and 0 to 50% by weightof a matrix resin (B) including one or more selected from the groupconsisting of an alkyl methacrylate polymer and an alkylmethacrylate-alkyl acrylate copolymer, wherein the total content ofalkyl acrylate is 20 to 50% by weight, a transparency (haze value)measured according to ASTM D-1003 under a condition of 0.15 mm thicknessis 2 or less, a transparency measured under a condition of 3 mmthickness is 4 or less, and an elution amount of butyl acrylate under acondition of using acetone is 0.01 or more. In this case, transparency,impact resistance, weather resistance, and molding processability areexcellent. In addition, whitening does not occur when bent. That is,non-whitening properties are excellent.

In this description, when measuring gel content, 30 g of acetone isadded to 0.5 g of dry powder of a thermoplastic resin, agitation isperformed at 210 rpm at room temperature for 12 hours using a shaker(SKC-6075, Lab Companion Co.), centrifugation is performed at 18,000 rpmat ° C. for 3 hours using a centrifuge (Supra R30, Hanil Science Co.) toseparate only insoluble matter that is not dissolved in acetone, and theseparated insoluble matter is dried in a forced circulation manner at85° C. for 12 hours using a forced convection oven (OF-12GW, LabCompanion Co.). Then, the weight of the dried insoluble matter ismeasured, and gel content is calculated by Equation 2 below.

Gel content (%)={Weight of insoluble matter(gel)/Weight ofsample}×100  [Equation 2]

In this description, when measuring grafting degree, 30 g of acetone isadded to 0.5 g of dry powder of a graft polymer, agitation is performedat 210 rpm at room temperature for 12 hours using a shaker (SKC-6075,Lab Companion Co.), centrifugation is performed at 18,000 rpm at ° C.for 3 hours using a centrifuge (Supra R30, Hanil Science Co.) toseparate only insoluble matter that is not dissolved in acetone, and theseparated insoluble matter is dried in a forced circulation manner at85° C. for 12 hours using a forced convection oven (OF-12GW, LabCompanion Co.). Then, the weight of the dried insoluble matter ismeasured, and grafting degree is calculated by Equation 3 below.

Grafting degree (%)=[Weight (g) of grafted monomers/Weight (g) ofrubber]×100  [Equation 3]

In Equation 3, the weight of grafted monomers is a value obtained bysubtracting the weight (g) of rubber from the weight of insoluble matter(gel) obtained by dissolving a graft copolymer in acetone and performingcentrifugation, and the weight (g) of rubber is the amount of rubbercomponents theoretically included in the graft copolymer powder.

In this description, DLS average particle diameter may be measured bydynamic light scattering, and specifically, may be measured as anintensity value using a sample in the form of latex and using a particlesize analyzer (Nicomp CW380, PPS Co.) in a Gaussian mode. As aparticular example, 0.1 g of latex having a solids content of 35 to 50%by weight is diluted with 100 g of deionized water to prepare a sample,and the DLS average particle diameter of the sample may be measured at23° C. using a particle size analyzer (Nicomp CW380, PPS Co.) in ameasurement method of using an auto-dilution manner and flow cells andin a measurement mode of dynamic light scattering/intensity 300kHz/intensity-weight Gaussian analysis.

In this description, TEM average particle diameter may be measured bytransmission electron microscope (TEM) analysis. Specifically, the TEMaverage particle diameter refers to a value obtained by numericallymeasuring particle size on a high magnification image of a TEM andaveraging the measurement results. In this case, a specific measurementexample is as follows:

-   -   Sample preparation: Thermoplastic resin pellets prepared using        an extrusion kneader.    -   Sample pretreatment: Trimming (23° C.)→hydrazine treatment (72°        C., 5 days)→sectioning (−120° C.)→OsO₄ vapor staining (2 hours)    -   Analyzer: TEM (JEM-1400, Jeol Co.)    -   Analysis conditions: Acc. Volt: 120 kV, spot size: 1 (×10K,        ×25K, ×50K)    -   Size (average particle diameter) measurement: An average value        of the largest diameters of each of particles in the top 10% of        a particle diameter distribution is measured.

Here, the average value of the largest diameters of each of particles inthe top 10% of a particle diameter distribution may mean an arithmeticmean value of the top % of the largest diameters of each of 100 or moreparticles randomly selected from a TEM image.

Hereinafter, each component constituting the thermoplastic resin of thepresent invention will be described in detail.

(A) Copolymer

The copolymer (A) includes an alkyl acrylate and an alkyl methacrylate,and is included in an amount of 50 to 100% by weight based on 100% byweight in total of the thermoplastic resin.

For example, based on 100% by weight in total of the copolymer (A), thecopolymer (A) may include 25 to 50% by weight, preferably 30 to 50% byweight, more preferably 35 to 50% by weight of an alkyl acrylate rubber(a-1) having a DLS average particle diameter of 40 to 120 nm or a TEMaverage particle diameter of 25 to 100 nm and 50 to 75% by weight,preferably 50 to 70% by weight, more preferably 50 to 65% by weight ofan alkyl acrylate-alkyl methacrylate copolymer (a-2). Within this range,transparency, gloss, non-whitening properties, and impact resistance areexcellent. The rubber (a-1) may have a DLS average particle diameter ofpreferably 45 to 110 nm, more preferably 50 to 100 nm, and a TEM averageparticle diameter of, preferably, 27 to 95 nm, more preferably 30 to 90nm. Within this range, excellent transparency and weather resistance areprovided without lowering the mechanical strength.

In this description, the graft copolymer (A) including the alkylacrylate rubber (a-1) and the alkyl acrylate-alkyl methacrylatecopolymer (a-2) refers to a graft copolymer (A) including the alkylacrylate rubber (a-1) and the alkyl acrylate-alkyl methacrylatecopolymer (a-2) surrounding the alkyl acrylate rubber (a-1). Inaddition, the graft copolymer (A) may be represented as a graftcopolymer (A) formed by graft-polymerizing an alkyl acrylate and analkyl methacrylate onto the alkyl acrylate rubber (a-1).

For example, the copolymer (A) may have a grafting degree of 60 to 200%and a weight average molecular weight of 40,000 to 120,000 g/mol. Withinthese ranges, molding processability and non-whitening properties may beexcellent. The copolymer (A) preferably has a grafting degree of 60 to150%, more preferably 65 to 130%. Within this range, non-whiteningproperties may be excellent without deterioration in impact resistanceand molding processability. The copolymer (a-2) preferably has a weightaverage molecular weight of 40,000 to 110,000 g/mol, more preferably50,000 to 100,000 g/mol. Within this range, molding processability andnon-whitening properties may be excellent without deterioration inimpact resistance.

In this description, unless otherwise defined, weight average molecularweight may be measured using gel permeation chromatography (GPC, WatersBreeze). As a specific example, the weight average molecular weight maybe measured using tetrahydrofuran (THF) as an eluate through gelpermeation chromatography (GPC, Waters Breeze). In this case, weightaverage molecular weight is obtained as a relative value to apolystyrene (PS) standard sample. As a specific measurement example, theweight average molecular weight may be measured under conditions ofsolvent: THF, column temperature: 40° C., flow rate: 0.3 ml/min, sampleconcentration: 20 mg/ml, injection amount: 5 μl, column model: 1× PLgel10 μm MiniMix-B (250×4.6 mm)+1× PLgel 10 μm MiniMix-B (250×4.6 mm)+1×PLgel 10 μm MiniMix-B Guard (50×4.6 mm), equipment name: Agilent 1200series system, refractive index detector: Agilent G1362 RID, RItemperature: 35° C., data processing: Agilent ChemStation S/W, and testmethod (Mn, Mw and PDI): OECD TG 118.

For example, the rubber (a-1) may have a glass transition temperature of−50 to −20° C., preferably −48 to −° C. Within this range, impactstrength is further improved without deterioration of other physicalproperties.

In this description, glass transition temperature may be measured at aheating rate of 10° C./min using a differential scanning calorimeter (TAInstruments Q100 DSC) according to ASTM D 3418.

For example, the rubber (a-1) may further include an alkyl methacrylate.In this case, chemical resistance and impact resistance may be furtherimproved. For example, the content of the alkyl methacrylate included inthe rubber (a-1) may be 0.1 to 25% by weight, preferably 1 to 20% byweight, more preferably 2 to 15% by weight based on 100% by weight intotal of the rubber (a-1). Within this range, desired effects may besufficiently obtained without deterioration in other physicalproperties.

For example, the alkyl acrylate rubber may be prepared by emulsionpolymerization of an alkyl acrylate-based compound. As a specificexample, the acrylate rubber may be prepared by mixing an acrylate-basedcompound, an emulsifier, an initiator, a grafting agent, a crosslinkingagent, an electrolyte, and a solvent and performing emulsionpolymerization of the mixture. In this case, grafting efficiency mayincrease, thereby improving physical properties such as impactresistance.

For example, based on 100% by weight of the copolymer (a-2), thecopolymer (a-2) may include 80 to 99.9% by weight of alkyl methacrylateand 0.1 to 20% by weight of alkyl acrylate, preferably 85 to 99.5% byweight of alkyl methacrylate and 0.5 to 15% by weight of alkyl acrylate,more preferably 85 to 99% by weight of alkyl methacrylate and 1 to 15%by weight of alkyl acrylate. Within this range, impact strength andweather resistance may be further improved.

For example, the rubber (a-1) may include a rubber seed.

For example, the rubber seed may be prepared by polymerizing alkylacrylate and, optionally alkyl methacrylate. When alkyl methacrylate isincluded, the alkyl methacrylate may be included in an amount of 0.1 to25% by weight, preferably 1 to 20% by weight, more preferably 2 to 15%by weight based on 100% by weight of the rubber seed. Within this range,impact strength, weather resistance, and physical property balance areexcellent.

As a specific example, the rubber seed may be prepared by polymerizingan alkyl acrylate with 0.01 to 3 parts by weight of a crosslinkingagent, 0.01 to 3 parts by weight of an initiator, and 0.01 to 5 parts byweight of an emulsifier based on 100 parts by weight of unitsconstituting the copolymer (A). Within this range, a polymer having aneven size may be prepared within a short time, and physical propertiessuch as weather resistance and impact strength may be further improved.

As another specific example, based on 100 parts by weight of unitsconstituting the copolymer (A), the rubber seed may be prepared byadding 0.1 to 1 part by weight of a crosslinking agent, 0.01 to 1 partby weight of an initiator, and 0.1 to 3.0 parts by weight of anemulsifier to monomers including an alkyl acrylate and an alkylmethacrylate and performing polymerization. Within this range, a polymerhaving an even size may be prepared within a short time, and physicalproperties such as weather resistance and impact strength may be furtherimproved.

For example, based on 100 parts by weight of units constituting thecopolymer (A), the copolymer (A) may be prepared by a method including astep (A-1) of preparing a rubber seed by polymerizing a mixturecontaining 0.001 to 1 part by weight of an electrolyte, 0.01 to 5 partsby weight of a crosslinking agent, 0.01 to 3 parts by weight of aninitiator, and 0.01 to 5 parts by weight of an emulsifier with 1 to 15parts by weight of an alkyl acrylate and optionally an alkylmethacrylate; a step (A-2) of preparing a rubber core by polymerizing,in the presence of the rubber seed, a mixture containing 20 to 50 partsby weight of an alkyl acrylate and optionally an alkyl methacrylate,0.01 to 1 part by weight of a crosslinking agent, 0.01 to 3 parts byweight of an initiator, and 0.01 to 5 parts by weight of an emulsifier;and a step (A-3) of preparing a graft shell by adding 0.01 to 3 parts byweight of a crosslinking agent, 0.01 to 3 parts by weight of aninitiator, 0.1 to 2 parts by weight of an emulsifier, and 0.01 to 1 partby weight of an activator to 40 to 75 parts by weight of the sum of analkyl acrylate and an alkyl methacrylate in the presence of the rubbercore and mixing the components. In this case, the physical propertybalance of impact resistance, weather resistance, moldingprocessability, and non-whitening properties are excellent.

In this description, for example, the alkyl acrylate compound may be analkyl acrylate containing an alkyl group having 1 to 15 carbon atoms,and as a specific example, may include one or more selected from thegroup consisting of methyl acrylate, ethyl acrylate, propyl acrylate,butyl acrylate, 2-ethylbutyl acrylate, octyl acrylate, 2-ethylhexylacrylate, hexyl acrylate, heptyl acrylate, n-pentyl acrylate, and laurylacrylate. As another example, the alkyl acrylate compound preferably isan alkyl acrylate containing a chain alkyl group having 1 to 4 carbonatoms, more preferably butyl acrylate.

In this description, for example, the alkyl methacrylate may be an alkylmethacrylate containing an alkyl group having 1 to 15 carbon atoms, andas a specific example, may include one or more selected from the groupconsisting of methyl methacrylate, ethyl methacrylate, butylmethacrylate, 2-ethylbutyl methacrylate, 2-ethylhexyl methacrylate, andlauryl methacrylate. The alkyl methacrylate preferably is an alkylmethacrylate containing a chain alkyl group having 1 to 4 carbon atoms,more preferably methyl methacrylate.

In this description, unless otherwise defined, crosslinking agentscommonly used in the art to which the present invention pertains may beused in the present invention without particular limitation. Forexample, one or more compounds including an unsaturated vinyl group andcapable of serving as a crosslinking agent, or one or more compoundsincluding two or more unsaturated vinyl groups having differentreactivities may be used as the crosslinking agent of the presentinvention. As a specific example, the crosslinking agent of the presentinvention may include one or more selected from the group consisting ofpolyethyleneglycol diacrylate, polyethyleneglycol dimethacrylate,polypropyleneglycol diacrylate, polypropyleneglycol dimethacrylate,ethyleneglycol diacrylate, ethyleneglycol dimethacrylate,divinylbenzene, diethyleneglycol dimethacrylate, triethyleneglycoldimethacrylate, 1,3-butadiol dimethacrylate, hexanediol propoxylatediacrylate, neopentylglycol dimethacrylate, neopentylglycol ethoxylatediacrylate, neopentylglycol propoxylate diacrylate, trimethylolpropanetrimethacrylate, trimethylolmethane triacrylate, trimethylpropaneethoxylate triacrylate, trimethylpropane propoxylate triacrylate,pentaerythritol ethoxylate triacrylate, pentaerythritol propoxylatetriacrylate, vinyltrimethoxysilane, allyl methacrylate, triallylisocyanurate, triallyl amine, and diallyl amine, without being limitedthereto.

In this description, for example, a mixture containing one or moreselected from the group consisting of KCl, NaCl, KHCO₃, NaHCO₃, K₂CO₃,Na₂CO₃, KHSO₃, NaHSO₃, K₄P₂O₇, Na₄P₂O₇, K₃PO₄, Na₃PO₄, K₂HPO₄, Na₂HPO₄,KOH, NaOH, and Na₂S₂O₇ may be used as the electrolyte, without beinglimited thereto.

In this description, initiators commonly used in the art to which thepresent invention pertains may be used in the present invention withoutparticular limitation. For example, radical initiators such aswater-soluble initiators and fat-soluble initiators may be used, and amixture containing one or more of the radical initiators may be used.

The water-soluble initiator may include one or more selected from thegroup consisting of inorganic peroxides including sodium persulfate,potassium persulfate, ammonium persulfate, potassium superphosphate, andhydrogen peroxide, without being limited thereto.

The fat-soluble initiator may include one or more selected from thegroup consisting of dialkyl peroxides, diacyl peroxides, diperoxyketals,hydroperoxides, peroxyesters, peroxydicarbonates, and azo compounds.

As a more specific example, the fat-soluble initiator may include one ormore selected from the group consisting of organic peroxides such ascumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide,dicumyl peroxide, t-butylcumyl peroxide, di-t-amyl peroxide,2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, 1,1,-di(t-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-di(t-butylperoxy)-cyclohexane, 1,1-di(t-amylperoxy)-cyclohexane,ethyl 3,3-di(t-amylperoxy)-butyrate, diisopropylbenzenemono-hydroperoxide, t-amyl hydroperoxide, t-butyl hydroperoxide, t-butylperoxyneodecanoate, t-butyl peroxypivalate,di-(3,5,5-trimethylhexanoyl)-peroxide, t-butyl peroxy-2-ethylhexanoate,t-butyl peroxy-3,5,5-trimethylhexanoate, t-amyl peroxy neodecanoate,t-amyl peroxypivalate, t-amyl peroxy-2-ethylhexanoate, t-butylperoxyacetate, t-butyl peroxybenzoate, t-amyl peroxy 2 ethylhexylcarbonate, t-butyl peroxy 2-ethylhexyl carbonate, t-butyl peroxyisopropyl monocarbonate, t-butyl peroxy maleic acid, cumylperoxyneodecanoate, 1,1,3,3,-tetramethylbutyl peroxy neodecanoate,1,1,3,3,-tetramethylbutyl peroxy 2-ethylhexanoate, di-2-ethylhexylperoxydicarbonate, 3-hydroxy-1,1-dimethylbutylperoxy neodecanoate,acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoylperoxide, dilauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, andt-butyl peroxy isobutyrate; azobisisobutyronitrile;azobismethylbutyronitrile; azobis-4-methoxy-2,4-dimethylvaleronitrile;azobis-2,4-dimethylvaleronitrile; azobis cyclohexanecarbonitrile; andazobis isobutyric acid methyl, without being limited thereto.

In the step of preparing a rubber seed, the step of preparing a rubbercore, and the step of preparing a copolymer shell (graft shell), inaddition to the initiator, an oxidation-reduction catalyst may beoptionally used to further accelerate initiation reaction. For example,the oxidation-reduction catalyst may include one or more selected fromthe group consisting of sodium pyrophosphate, dextrose, ferrous sulfide,sodium sulfite, sodium formaldehyde sulfoxylate, sodiumethylenediaminetetraacetate, sulfonato acetic acid metal salt, andsulfinato acetic acid metal salt without being limited thereto.

In at least one step of the step of preparing a rubber seed, the step ofpreparing a rubber core, and the step of preparing a copolymer shell(graft shell), in addition to the polymerization initiator, an activatoris preferably used to promote initiation reaction of peroxides. Theactivator preferably includes one or more selected from the groupconsisting of sodium formaldehyde, sulfoxylate, sodium ethylenediamine,tetraacetate, ferrous sulfate, dextrose, sodium pyrrolate, sodiumsulfite, sulfonato acetic acid metal salt, and sulfinato acetic acidmetal salt.

Based on 100 parts by weight in total of monomers added to prepare thecopolymer (A), the activator may be added in an amount of 0.01 to 3parts by weight or 0.01 to 1 part by weight. Within this range,polymerization rate may increase.

In the step of preparing a seed and the step of preparing a core, as amethod of feeding monomers, batch feed or continuous feed may be usedalone, or two methods may be used in combination.

In this description, “continuous feed” means that components are not fedbatchwise. For example, according to continuous feed, components may befed for 10 minutes or more, 30 minutes or more, 1 hour or more,preferably 2 hours or more within a polymerization time range in drop bydrop, little by little, step by step, or continuous flow.

In this description, emulsifiers commonly used in the art to which thepresent invention pertains may be used in the present invention withoutparticular limitation. For example, the emulsifier of the presentinvention may include one or more selected from the group consisting oflow-molecular weight carboxylates having 20 or fewer carbon atoms or 10to 20 carbon atoms, such as rosin acid salt, lauric acid salt, oleicacid salt, and stearic acid salt; alkyl sulfosuccinates having 20 orfewer carbon atoms or 10 to 20 carbon atoms or derivatives thereof;alkyl sulfates or sulfonates having 20 or fewer carbon atoms or 10 to 20carbon atoms; polyfunctional carboxylic acids having 20 to 60, 20 to 55,or 30 to 55 carbon atoms and having two or more carboxy groups,preferably 2 to 3 carboxy groups, or salts thereof; and one or morephosphoric acid salts selected from the group consisting of mono alkylether phosphates and dialkyl ether phosphates.

As another example, the emulsifier may include one or more selected fromthe group consisting of reactive emulsifiers selected from the groupconsisting of sulfoethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, sodium styrene sulfonate, sodium dodecyl allylsulfosuccinate, a copolymer of styrene and sodium dodecyl allylsulfosuccinate, polyoxyethylene alkylphenyl ether ammonium sulfates,C16-18 alkenyl succinic acid di-potassium salt, and sodium methallylsulfonate; and non-reactive emulsifiers selected from the groupconsisting of alkyl aryl sulfonate, alkali methyl alkyl sulfate,sulfonated alkyl esters, fatty acid soap, and alkali salts of rosinacid.

As another example, the derivatives of C12 to C18 alkyl sulfosuccinatemetal salts, C12 to C20 alkyl sulfate esters, or the derivatives ofsulfonic acid metal salts may be used as the emulsifier. For example,the derivatives of C12 to C18 alkyl sulfosuccinate metal salts mayinclude sodium or potassium salts of dicyclohexyl sulfonate, dihexylsulfosuccinate, and dioctyl sulfosuccinate, and the C12 to C20 alkylsulfate esters or the sulfonic acid metal salts may include alkylsulfate metal salts such as sodium lauric sulfate, sodium dodecylsulfate, sodium dodecyl benzene sulfate, sodium octadecyl sulfate,sodium oleic sulfate, potassium dodecyl sulfate, and potassium octadecylsulfate. The emulsifiers may be used alone or in combination thereof.

In this description, a derivative of a compound refers to a substanceobtained by substituting at least one of hydrogen and a functional groupof the compound with another type of group such as an alkyl group or ahalogen group.

In this description, when preparing the copolymer (A), a molecularweight modifier may be optionally included, and then emulsionpolymerization may be performed. Based on 100 parts by weight of unitsconstituting the copolymer (A), the molecular weight modifier may beincluded in an amount of 0.01 to 2 parts by weight, 0.05 to 2 parts byweight, or 0.05 to 1 part by weight. Within this range, a polymer havinga desired molecular weight may be easily prepared.

For example, the molecular weight modifier may include one or moreselected from the group consisting of mercaptans such as α-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, and octylmercaptan; halogenated hydrocarbons such as carbon tetrachloride,methylene chloride, and methylene bromide; and sulfur-containingcompounds such as tetra ethyl thiuram disulfide, dipentamethylenethiuram disulfide, and diisopropylxanthogen disulfide, and preferablyincludes mercaptan compounds such as tert-dodecylmercaptan, withoutbeing limited thereto.

When emulsion polymerization is performed, polymerization temperature isnot particularly limited. In general, emulsion polymerization may beperformed at 50 to 85° C., preferably 60 to 80° C.

For example, the copolymer latex (A) prepared in the above step may havea coagulum content of 1% or less, preferably 0.5% or less, still morepreferably 0.1% or less. Within this range, the productivity of a resinmay be increased, and mechanical strength and appearance properties maybe improved.

In this description, the weight of coagulum produced in a reactor, thetotal weight of rubber, and the weight of monomers are measured, andcoagulum content (%) is calculated by Equation 4 below.

Solid coagulum (%)=[Weight (g) of coagulum produced in reactor/Totalweight (g) of rubber and monomers]×100  [Equation 4]

For example, the latex of the copolymer (A) may be prepared in the formof powder through a conventional process including coagulation, washing,and drying. As a specific example, a metal salt or an acid is added,coagulation is performed at 60 to 100° C., and aging, dehydration,washing, and drying are performed to prepare the latex of the copolymer(A) in the form of powder, but the present invention is not limitedthereto.

Other conditions not specified in the method for preparing theabove-described copolymer (A), i.e., polymerization conversion rate,reaction pressure, reaction time, gel content, etc., are notparticularly limited when the conditions are within the ranges commonlyused in the technical field to which the present invention pertains. Theabove conditions may be appropriately selected and used when necessary.

In this description, “%” means “% by weight” unless defined otherwise.

(B) Matrix Resin

Based on 100% by weight in total of the thermoplastic resin of thepresent invention, the thermoplastic resin includes 0 to 50% by weightof a matrix resin including one or more selected from the groupconsisting of an alkyl methacrylate polymer and an alkylmethacrylate-alkyl acrylate copolymer. When the matrix resin (B) isincluded in the thermoplastic resin, mechanical properties and moldingprocessability may be further improved.

The matrix resin (B) is a hard matrix capable of being melt-kneaded withthe dry powder (DP) of the copolymer (A), and includes a hardpolymer-forming monomer having a glass transition temperature of 60° C.or higher. The matrix resin (B) preferably has a glass transitiontemperature of 80 to 160° C., more preferably 90 to 150° C. Within thisrange, molding processability may be further improved.

The matrix resin (B) may include one or more selected from the groupconsisting of an alkyl methacrylate polymer and an alkylmethacrylate-alkyl acrylate copolymer. Preferably, the matrix resin (B)may be an alkyl methacrylate polymer. In this case, transparency isfurther improved without deterioration in other properties.

The alkyl methacrylate-alkyl acrylate copolymer that may be included inthe matrix resin (B) differs from the graft copolymer (A).

Each of the alkyl methacrylate and the alkyl acrylate included in thematrix resin may be appropriately selected within the same range asthose referred regarding the graft copolymer (A).

Preferably, the alkyl methacrylate included in the matrix resin may bemethyl methacrylate.

Preferably, the alkyl acrylate included in the matrix resin may be oneor more selected from the group consisting of methyl acrylate and ethylacrylate.

The matrix resin (B) may be prepared by a commonly known method. Whenpreparing the matrix resin (B), one or more of an initiator, acrosslinking agent, and a molecular weight modifier may be included whennecessary. The matrix resin (B) may be prepared by suspensionpolymerization, emulsion polymerization, bulk polymerization, orsolution polymerization.

Materials required for reaction such as solvents and emulsifiers orconditions such as polymerization temperature and polymerization time,which are to be added or changed according to polymerization methods,may be appropriately selected without particular limitation when thematerials and the conditions are generally applicable depending on apolymerization method selected for the preparation of a matrix resin.

As another example, a commercially available matrix resin may be used asthe matrix resin (B).

Thermoplastic Resin

Based on 100% by weight in total of the thermoplastic resin of thepresent invention, the thermoplastic resin may include 50 to 100% byweight of the copolymer (A) and 0 to 50% by weight of the matrix resin(B), preferably 60 to 100% by weight of the copolymer (A) and 0 to 40%by weight of the matrix resin (B), more preferably 60 to 90% by weightof the copolymer (A) and 10 to 40% by weight of the matrix resin (B).Within this range, impact resistance, fluidity, and non-whiteningproperties may be excellent.

The total content of the alkyl acrylate included in 100% by weight intotal of the thermoplastic resin may be 20 to 50% by weight, preferably22 to 50% by weight, more preferably 25 to 50% by weight. Within thisrange, impact strength and non-whitening properties may be excellentwithout deterioration in weather resistance.

In this description, the total content of the alkyl acrylate included in100% by weight in total of the thermoplastic resin refers to the sum ofthe total weight of the alkyl acrylate compounds respectively includedin the copolymer (A) and the matrix resin (B), and may be calculated,for example, by summing the weights (parts by weight) of alkyl acrylatecompounds fed to prepare the thermoplastic resin. As another example,the total content of the alkyl acrylate may be quantitatively determinedby subjecting the thermoplastic resin to nuclear magnetic resonance(NMR) analysis or Fourier transform infrared spectroscopy (FT-IR)analysis.

In this description, NMR analysis means analysis by ¹H NMR unlessotherwise specified.

In this description, NMR analysis may be performed according to a methodcommonly practiced in the art, and a specific measurement example is asfollows.

-   -   Equipment name: Bruker 600 MHz NMR (AVANCE III HD) CPP BB (1H        19F tunable and broadband, with z-gradient) Prodigy Probe    -   Measurement conditions: ¹H NMR (zg30):ns=32, d1=5 s, TCE-d2, at        room temp.

In this description, FT-IR analysis may be performed according to amethod commonly practiced in the art, and a specific measurement exampleis as follows.

-   -   Equipment name: Agilent Cary 660    -   Measurement conditions: ATR mode

The thermoplastic resin may have a butyl acrylate coverage value (X) of50% or more, preferably 50 to 250%, more preferably 55 to 200% ascalculated by Equation 1 below through the limited composition asdescribed above. Within this range, non-whitening is further improved.

X(%)={(G−Y)/Y}*100  [Equation 1]

wherein G represents the total gel content (%) of the thermoplasticresin, and Y represents the content (% by weight) of butyl acrylate inthe gel contained in the thermoplastic resin.

In Equation 1, the content of butyl acrylate in the gel of thethermoplastic resin refers to the content (based on based on 100% byweight in total of the fed thermoplastic resin) of butyl acrylate ininsoluble matter (gel) obtained in the aforementioned process ofdetermining gel content. Here, the gel content refers to the content (%by weight) of the insoluble matter based on 100% by weight in total ofthe thermoplastic resin.

The thermoplastic resin may include one or more types of alkyl acrylatecompounds. Specifically, a thermoplastic resin exhibiting excellentnon-whitening properties together with excellent mechanical propertiessuch as excellent impact resistance, excellent molding processability,excellent gloss can be provided by limiting the difference between thetotal gel content and the content of butyl acrylate in the gel withrespect to the content of butyl acrylate in the gel of butyl acrylateincluded in the thermoplastic resin into a specific range.

In addition, the transparency (haze value) of the thermoplastic resinmeasured according to ASTM D-1003 under a condition of 0.15 mm thicknessaccording to the aforementioned limited composition may be 2 or less,preferably 1.8 or less, more preferably 1.5 or less, and thetransparency measured under a condition of 3 mm thickness may be 4 orless, preferably 3.8 or less, more preferably 3.5 or less. Within thisrange, the thermoplastic resin exhibits excellent transparency, therebyproving a finishing material having excellent appearance quality.

The haze of the thermoplastic resin can be measured using a method knownin the related art for measuring transparency. Particularly, the hazemay be measured according to ASTM D1003. As a particular example, thehaze value may be measured at 23° C. according to ASTM D1003 using ahaze meter (model name: HM-150) manufactured by MURAKAMI. Here, a filmspecimen extruded to a thickness of 0.15 mm at an extrusion temperatureof 230° C. may be used as the specimen having a thickness of 0.15 mm,and a specimen injected to a thickness of 3 mm at a barrel temperatureof 220° C. may be used as the specimen having a thickness of 3 mm.

When elution of the thermoplastic resin is performed using acetone, theelution amount of butyl acrylate is preferably 0.01% by weight or more,more preferably 0.1% by weight or more, as a preferred example, 0.1 to15% by weight, as a more preferred example, 0.5 to 15% by weight. Withinthis range, non-whitening properties may be excellent.

In this description, when measuring the elution amount of alkyl acrylateusing acetone, 30 g of acetone is added to 0.5 g of dry powder of athermoplastic resin, agitation is performed at 210 rpm at roomtemperature for 12 hours using a shaker (SKC-6075, Lab Companion Co.),centrifugation is performed at 18,000 rpm at 0° C. for 3 hours using acentrifuge (Supra R30, Hanil Science Co.) to obtain an acetone solutionfrom which insoluble matter is separated, and the obtained acetonesolution is dried in a forced circulation manner at 85° C. for 12 hoursusing a forced convection oven (OF-12GW, Lab Companion Co.) to obtain aresin sol. Then, NMR analysis or FT-IR analysis is performed on theresin sol to quantitatively determine the elution amount of an alkylacrylate.

A difference of refractive index (according to ASTM D542) between a soland a gel of the thermoplastic resin under a condition of using acetonemay be, for example, 0.02 or less, preferably 0.005 to 0.02, morepreferably 0.009 to 0.019. Within this range, transparency is furtherimproved without deterioration of other physical properties.

In the description, the refractive index difference between a sol and agel can be obtained as follows: 30 g of acetone is added to 0.5 g of drypowder of the thermoplastic resin, agitation is performed at 210 rpm atroom temperature for 12 hours using a shaker (SKC-6075, Lab CompanionCo.), centrifugation is performed at 18,000 rpm at 0° C. for 3 hoursusing a centrifuge (Supra R30, Hanil Science Co.) to obtain an acetonesolution from which insoluble matter is separated, and then, thedissolved portion is dried in a forced circulation manner at 85° C. for12 hours using a forced convection oven (OF-12GW, Lab Companion Co.) toobtain a sol, and the separated insoluble matter is dried in a forcedcirculation manner at 85° C. for 12 hours using a forced convection oven(OF-12GW, Lab Companion Co.) to obtain a gel. Then, a refractive indexof each of the sol and the gel is measured according to ASTM D542. Thepresent invention can provide a thermoplastic resin having more improvedtransparency by controlling a refractive index difference between a soland a gel within the above range.

In this description, the refractive index may be measured using an Abberefractometer at 25° C. according to ASTM D542.

When the thermoplastic resin includes the matrix resin (B), a refractiveindex difference between the rubber (a-1) of the copolymer (A) and thematrix resin (B) included therein may be for example 0.02 or more,preferably 0.02 to 0.04, more preferably 0.02 to 0.03. Within thisrange, desired effects can be sufficiently realized withoutdeterioration in other properties.

Even when a refractive index difference between the rubber particles andthe matrix is 0.02 or more, a refractive index difference between thesol and gel of the thermoplastic resin may be adjusted to 0.02 or lessas described above, whereby the transparency of the thermoplastic resinis further improved.

The thermoplastic resin, the rubber (a-1), or both of them may have aglass transition temperature of, for example, −50 to −20° C., preferably−48 to −21° C. Within this range, impact strength is further improvedwithout deterioration in other properties.

The thermoplastic resin of the present invention has excellent whiteningresistance when bending or folding. For example, when the thermoplasticresin is extruded into a film having a width and length of 100 mm×100 mmand a thickness of 0.15 mm and the film is bent at 180° at a temperatureof 23° C., whitening does not occur, indicating that non-whiteningproperties are excellent.

In addition, the thermoplastic resin of the present invention hasexcellent whitening resistance against external impact (hit). Forexample, when the thermoplastic resin is extruded into a film having athickness of 0.15 mm and a weight having a weight of 1 kg is verticallydropped onto the film from a height of 100 mm at a temperature of 23° C.using a Gardner impact tester, a difference in haze values measuredbefore and after impact according to ASTM D1003-95 for an area hit bythe weight may be 10 or less, preferably 5 or less, more preferably 3 orless. In this case, when bending or external impact is applied,whitening is significantly reduced, and thus problems such as inhibitionof expression of intrinsic color due to whitening, deterioration ofappearance quality, and reduction of luxuriousness may be prevented,thereby providing a molded article having excellent appearance quality.

In this description, specifically, when a difference in haze valuesbefore and after impact is measured, impact is applied to the middleportion of a film having a thickness of 0.15 mm and a width and lengthof 100 mm×100 mm using a weight (Falling Weight 1 kg, Cat. No. 1249) andusing a Gardner impact tester (Impact Tester 5545, BYK Gardner Co.),haze values before and after impact are measured for the middle portionof the film, and a difference in haze values before and after impact iscalculated based the measured values.

The haze value before and after impact may be measured using a methodknown for measuring transparency in the related field, and in detail,may be measured according to ASTM D1003. As a specific example, the hazevalue of a film extruded at an extrusion temperature of 230° C. may bemeasured at 23° C. using a haze meter (model name: HM-150, MURAKAMI Co.)according to ASTM D1003.

For example, the thermoplastic resin may have a gloss of 110 or more,preferably 110 to 150, more preferably 115 or 150, still more preferably120 to 140 as measured at an incidence angle of 60° according to ASTMD528. Within this range, gloss may be excellent without deterioration inother physical properties, thereby providing a molded article havingexcellent appearance quality.

For example, the thermoplastic resin may have a melt index (MI) of 3g/10 min or more, preferably 3 to 20 g/10 min, more preferably 5 to 20g/10 min, still more preferably 7 to 15 g/10 min as measured accordingto ASTM D1238. Within this range, molding processability may beexcellent without deterioration in other physical properties.

In this description, a melt index may be measured at a temperature of220° C. for a reference time of 10 minutes under a load of 10 kgaccording to ASTM D1238. As a more particular example, a specimen isheated to 220° C. using a melt indexer (GOETTFERT Co.), the specimen isplaced in the cylinder of the melt indexer, and a load of 10 kg isapplied with a piston. At this time, the weight (g) of a resin meltedand flowing out for 10 minutes is measured, and a melt index iscalculated based on the measured value.

Method of Preparing Thermoplastic Resin

A method of preparing the thermoplastic resin of the present inventionincludes a step of kneading and extruding to 100 parts by weight of thealkyl acrylate-alkyl methacrylate graft copolymer (A) and 0 to 50 partsby weight of the matrix resin (B) including one or more selected fromthe group consisting of an alkyl methacrylate polymer and an alkylmethacrylate-alkyl acrylate copolymer, wherein an X value as measured byEquation 1 below is 50% or more. In this case, molding processability,transparency, gloss, and non-whitening properties may be excellent whilemaintaining mechanical properties to be equal to those of conventionalASA based resins, thereby providing excellent appearance quality.

X (%)={(G−Y)/Y}×100  [Equation 1]

In Equation 1, G represents the total gel content (%) of thethermoplastic resin, and Y represents the content (% by weight) of butylacrylate in the gel of the thermoplastic resin.

The copolymer (A) used in the preparation of the thermoplastic resin maybe prepared by the method of preparing the copolymer (A). In this case,grafting degree and molecular weight may be properly adjusted, and thusmolding processability and non-whitening properties may be excellent.

When the thermoplastic resin of the present invention is prepared, inthe step of kneading and extruding, when necessary, one or more selectedfrom the group consisting of a lubricant, a heat stabilizer, a lightstabilizer, an antioxidant, a ultraviolet light stabilizer, a dye, apigment, a colorant, a release agent, an antistatic agent, anantibacterial agent, a processing aid, a compatibilizer, a metaldeactivator, a flame retardant, a smoke suppressant, an anti-drip agent,a foaming agent, a plasticizer, a reinforcing agent, a filler, a mattingagent, an anti-friction agent, and an anti-wear agent may be furtherincluded in an amount of 0.01 to 5 parts by weight, 0.05 to 3 parts byweight, 0.05 to 2 parts by weight, or 0.05 to 1 part by weight based on100 parts by weight in total of the copolymer (A) and the matrix resin(B). Within this range, required physical properties may be implementedwithout deterioration in the intrinsic physical properties of an ASAresin.

For example, the lubricant may include one or more selected fromethylene bis stearamide, polyethylene oxide wax, magnesium stearate,calcium stearamide, and stearic acid, without being limited thereto.

For example, the antioxidant may include phenolic antioxidants,phosphorus antioxidants and the like, without being limited thereto.

For example, the light stabilizer may include HALS-based lightstabilizers, benzophenone-based light stabilizers, benzotriazol-basedlight stabilizers and the like, without being limited thereto.

For example, the antistatic agent may include one or more of anionicsurfactants, nonionic surfactants and the like, without being limitedthereto.

For example, the release agent may include one or more selected fromglycerinstearate, polyethylene tetra stearate and the like, withoutbeing limited thereto.

Molded Article

A molded article of the present invention includes the thermoplasticresin of the present invention having excellent non-whiteningproperties. In this case, weather resistance, impact resistance, moldingprocessability, gloss, and whitening resistance may be excellent,thereby providing excellent appearance quality. Thus, the molded articlemay be applied to film or sheet products.

For example, the molded article may be a finishing material. In thiscase, non-whitening properties may be excellent, and thus appearancequality may be excellent.

Hereinafter, the present invention will be described in more detail withreference to the following preferred examples. However, these examplesare provided for illustrative purposes only and should not be construedas limiting the scope and spirit of the present invention. In addition,it will be apparent to those skilled in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe present invention, and such changes and modifications are alsowithin the scope of the appended claims.

EXAMPLES Example 1

<Rubber Seed Preparation Step>

5 parts by weight of butyl acrylate, 1.0 part by weight of sodiumdodecyl sulfate, 0.1 parts by weight of ethylene glycol dimethacrylate,0.1 parts by weight of allyl methacrylate, 0.1 parts by weight of sodiumhydrogen carbonate, and 60 parts by weight of distilled water were fedinto a nitrogen-substituted reactor batchwise, temperature was raised to70° C., and then 0.1 parts by weight of potassium persulfate was addedthereto to initiate reaction. Then, polymerization was performed for 1hour.

<Rubber Core Preparation Step>

35 parts by weight of butyl acrylate, 0.5 part by weight of sodiumdodecyl sulfate, 0.5 parts by weight of ethylene glycol dimethacrylate,0.8 parts by weight of allyl methacrylate, 40 parts by weight ofdistilled water, and 0.1 parts by weight of potassium persulfate weremixed with the rubber seed, and the mixture was continuously fed into areactor at 70° C. for 2.0 hours. After feeding, polymerization wasfurther performed for 1 hour. After completion of the reaction, theaverage particle size of the obtained rubber polymer was 80 nm.

<Copolymer Shell Preparation Step>

A mixture prepared by homogeneously mixing 40 parts by weight ofdistilled water, 57 parts by weight of methyl methacrylate, 3 parts byweight of butyl acrylate, 1.0 part by weight of sodium dodecylbenzenesulfonate, 0.05 parts by weight of tert-dodecyl mercaptan, and 0.1 partsby weight of t-butyl hydroperoxide as an initiator and a mixed solutioncontaining 0.015 parts by weight of sodium ethylenediaminetetraacetateas an activator, 0.1 parts by weight of sodium formaldehyde sulfoxylate,and 0.002 parts by weight of ferrous sulfide were each continuously fedinto the reactor containing the rubber core at 75° C. for 3 hours toperform polymerization. After completion of the continuous feed,polymerization was further performed at 75° C. for 1 hour, andtemperature was cooled to 60° C. to terminate and prepare graftcopolymer latex.

After completion of the reaction, the grafting degree of the obtainedgraft copolymer was 85%, and the weight average molecular weight of theshell was 71,000 (g/mol).

<Graft Copolymer Powder Preparation>

1.0 part by weight of an aqueous calcium chloride solution was added tothe prepared graft copolymer latex, coagulation was performed at 60 to85° C. under atmospheric pressure, aging was performed at 70 to 95° C.,dehydration and washing were performed, and then drying was performedwith hot blast at 85° C. for 2 hours to obtain graft copolymer powder.

<Thermoplastic Resin Preparation>

70 parts by weight of the graft copolymer powder, 30 parts by weight ofa methyl methacrylate (BA611 manufactured by LGMMA) as a matrix resin,1.5 parts by weight of a lubricant, 1.0 part by weight of anantioxidant, and 1.5 parts by weight of an ultraviolet light stabilizerwere added and mixed. Upon preparation of a specimen for weatherresistance evaluation, 1 part by weight of black colorant wasadditionally added to and mixed with 100 parts by weight of the total ofthe graft copolymer and the matrix resin. The mixture was introducedinto a 36 pie extrusion kneader at a cylinder temperature of 220° C. toprepare pellets. The prepared pellets were injected using an injectionmachine at a barrel temperature of 220° C. to prepare a specimen formeasuring physical properties such as impact strength.

The butyl acrylate (BA) content of the prepared thermoplastic resin was30.1% (wt %), the glass transition temperature of the rubber was −47°C., a BA coverage value was 77.5%, and the elution amount of BA in aresin sol was 1.89%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.016, and a refractive index difference betweenthe rubber (the rubber seed and the rubber core containing the rubberseed) and the matrix resin was 0.03.

<Thermoplastic Resin Film Preparation>

The thermoplastic resin pellets were introduced into a 20 pi singleextrusion kneader equipped with a T-die at a cylinder temperature of230° C. to prepare a film having a thickness of 150 μm.

Example 2

Preparation processes were performed in the same manner as in Example 1,except that 25 parts by weight of butyl acrylate was used when preparinga rubber core, and 66.5 parts by weight of methyl methacrylate and 3.5parts by weight of butyl acrylate were used when preparing a copolymershell.

The grafting degree of the obtained graft copolymer was 130%, and theweight-average molecular weight of the shell was 62,000.

The BA content in the prepared thermoplastic resin was 23.5%, a BAcoverage value was 116%, and the elution amount of BA in a resin sol was2.1%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.013, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Example 3

Preparation processes were performed in the same manner as in Example 1,except that 45 parts by weight of butyl acrylate were used whenpreparing a rubber core, and 47.5 parts by weight of methyl methacrylateand 2.5 parts by weight of butyl acrylate were used when preparing acopolymer shell.

The grafting degree of the obtained graft copolymer was 62%, and theweight-average molecular weight of the shell was 79,000.

The BA content in the prepared thermoplastic resin was 36.8%, a BAcoverage value was 57.1%, and the elution amount of BA in a resin solwas 1.54%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.019, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Example 4

Preparation processes were performed in the same manner as in Example 1,except that 2.0 parts by weight of sodium dodecyl sulfate were used whenpreparing a rubber seed.

An average particle size of the obtained rubber polymer (rubber core)was 50 nm, a grafting degree of the graft copolymer was 79%, and theweight-average molecular weight of the shell was 50,000.

The BA content in the prepared thermoplastic resin was 30.1%, a BAcoverage value was 72.2%, and the elution amount of BA in a resin solwas 1.99%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.017, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Example 5

Preparation processes were performed in the same manner as in Example 1,except that 0.4 parts by weight of sodium dodecyl sulfate were used whenpreparing a rubber seed.

An average particle size of the obtained rubber polymer was 100 nm, agrafting degree of the graft copolymer was 89%, and the weight-averagemolecular weight of the shell was 80,000.

The BA content in the prepared thermoplastic resin was 30.1%, a BAcoverage value was 80.9%, and the elution amount of BA in a resin solwas 1.81%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.016, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Example 6

Preparation processes were performed in the same manner as in Example 1,except that 0.3 parts by weight of sodium dodecyl sulfate were used whenpreparing a rubber seed.

An average particle size of the obtained rubber polymer was 110 nm, agrafting degree of the graft copolymer was 92%, and the weight-averagemolecular weight of the shell was 100,000.

The BA content in the prepared thermoplastic resin was 30.1%, a BAcoverage value was 83.6%, and the elution amount of BA in a resin solwas 1.76%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.016, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Example 7

Preparation processes were performed in the same manner as in Example 1,except that 33.25 parts by weight of butyl acrylate and 1.75 parts byweight of methyl methacrylate were used when preparing a rubber core,and 0.95 parts by weight of sodium dodecyl sulfate, 4.75 parts by weightof butyl acrylate, and 0.25 parts by weight of methyl methacrylate wereused when preparing a rubber seed.

An average particle size of the obtained rubber polymer was 80 nm, agrafting degree of the graft copolymer was 97%, and the weight-averagemolecular weight of the shell was 68,000.

The BA content in the prepared thermoplastic resin was 28.7%, the glasstransition temperature of the rubber was −° C., a BA coverage value was97.3%, and the elution amount of BA in a resin sol was 1.65%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.015, and a refractive index difference betweenthe rubber and the matrix resin was 0.029.

Example 8

Preparation processes were performed in the same manner as in Example 1,except that 29.75 parts by weight of butyl acrylate and 5.25 parts byweight of methyl methacrylate were used when preparing a rubber core,and 0.9 parts by weight of sodium dodecyl sulfate, 4.25 parts by weightof butyl acrylate, and 0.75 parts by weight of methyl methacrylate wereused when preparing a rubber seed.

An average particle size of the obtained rubber polymer was 80 nm, agrafting degree of the graft copolymer was 103%, and the weight-averagemolecular weight of the shell was 52,000.

The BA content in the prepared thermoplastic resin was 25.9%, a rubberglass transition temperature was −30° C., a BA coverage value was125.2%, and the elution amount of BA in a resin sol was 1.52%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.013, and a refractive index difference betweenthe rubber and the matrix resin was 0.026.

Example 9

Preparation processes were performed in the same manner as in Example 1,except that 26.25 parts by weight of butyl acrylate and 8.75 parts byweight of methyl methacrylate were used when preparing a rubber core,0.8 parts by weight of sodium dodecyl sulfate, 3.75 parts by weight ofbutyl acrylate, and 1.25 parts by weight of methyl methacrylate wereused when preparing a rubber seed, and 59.7 parts by weight of methylmethacrylate and 0.3 parts by weight of butyl acrylate were used whenpreparing a shell.

An average particle size of the obtained rubber polymer was 80 nm, agrafting degree of the graft copolymer was 140%, and the weight-averagemolecular weight of the shell was 41,000.

The BA content in the prepared thermoplastic resin was 21.2%, a rubberglass transition temperature was −21° C., a BA coverage value was217.0%, and the elution amount of BA in a resin sol was 0.04%

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.009, and a refractive index difference betweenthe rubber and the matrix resin was 0.023.

Example 10

Preparation processes were performed in the same manner as in Example 1,except that 54 parts by weight of methyl methacrylate and 6 parts byweight of butyl acrylate were used when preparing a copolymer shell.

A grafting degree of the obtained graft copolymer was 81%, and theweight-average molecular weight of the shell was 76,000.

The BA content in the resin was 32.2%, a BA coverage value was 67.4%,and the elution amount of BA in a resin sol was 3.92%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.017, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Example 11

Preparation processes were performed in the same manner as in Example 1,except that 48 parts by weight of methyl methacrylate and 12 parts byweight of butyl acrylate were used when preparing a copolymer shell.

A grafting degree of the obtained graft copolymer was 76%, and theweight-average molecular weight of the shell was 95,000.

The BA content in the resin was 36.4%, the glass transition temperatureof the rubber was −35° C., a BA coverage value was 52.8%, and theelution amount of BA in a resin sol was 8.17%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.017, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Example 12

Preparation processes were performed in the same manner as in Example 2,except that, when preparing thermoplastic resin, a matrix resin was notused and the graft copolymer was used in an amount of 100 parts byweight.

The BA content in the resin was 33.5%, a BA coverage value was 116.0%,and the elution amount of BA in a resin sol was 5.00%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.012.

Comparative Example 1

Preparation processes were performed in the same manner as in Example 1,except that 55 parts by weight of butyl acrylate were used whenpreparing a rubber core, and 40 parts by weight of methyl methacrylatewere used when preparing a copolymer shell.

An average particle size of the obtained rubber polymer was 85 nm, agrafting degree of the graft copolymer was 38%, and the weight-averagemolecular weight of the shell was 82,000.

The BA content in the resin was 42.0%, the glass transition temperatureof the rubber was −47° C., a BA coverage value was 38.0%, and theelution amount of BA in a resin sol was 0%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.022, and a refractive index difference betweenthe rubber and the matrix resin was 0.03.

Comparative Example 2

Preparation processes were performed in the same manner as in Example 2,except that 20 parts by weight of butyl acrylate were used whenpreparing a rubber core, and 75 parts by weight of methyl methacrylatewere used when preparing a copolymer shell.

An average particle size of the obtained rubber polymer was 75 nm, agrafting degree of the graft copolymer was 100%, and the weight-averagemolecular weight of the shell was 71,000.

The BA content in the resin was 17.5%, the glass transition temperatureof the rubber was −47° C., a BA coverage value was 100.0%, and theelution amount of BA in a resin sol was 0%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.015, and a refractive index difference betweenthe rubber and the matrix resin was 0.029.

Comparative Example 3

Preparation processes were performed in the same manner as in Example 3,except that 0.11 parts by weight of sodium dodecyl sulfate were usedwhen preparing a rubber seed, and 50 parts by weight of methylmethacrylate were used to prepare a shell.

An average particle size of the obtained rubber polymer was 150 nm, agrafting degree of the graft copolymer was 98%, and the weight-averagemolecular weight of the shell was 126,000.

The BA content in the resin was 35.0%, a BA coverage value was 98.0%,and the elution amount of BA in a resin sol was 0%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.015, and a refractive index difference betweenthe rubber and the matrix resin was 0.030.

Comparative Example 4

Preparation processes were performed in the same manner as in Example 1,except that 0.75 parts by weight of sodium dodecyl sulfate, 3.5 parts byweight of butyl acrylate, and 1.5 parts by weight of methyl methacrylatewere used when preparing a rubber seed, 24.5 parts by weight of butylacrylate and 10.5 parts by weight of methyl methacrylate were used whenpreparing a rubber core, and 60 parts by weight of methyl methacrylatewere used when preparing a shell.

A grafting degree of the obtained graft copolymer was 120%, and theweight-average molecular weight of the shell was 32,000.

The BA content in the resin was 19.6%, the glass transition temperatureof the rubber was −14° C., a BA coverage value was 214.3%, and theelution amount of BA in a resin sol was 0%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.01, and a refractive index difference betweenthe rubber and the matrix resin was 0.021.

Comparative Example 5

Preparation processes were performed in the same manner as in Example 1,except that 45 parts by weight of methyl methacrylate and 15 parts byweight of butyl acrylate were used when preparing a shell.

A grafting degree of the obtained graft copolymer was 59%, and theweight-average molecular weight of the shell was 121,000.

The BA content in the resin was 38.5%, a BA coverage value was 38.6%,and the elution amount of BA in a resin sol was 11.48%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.018, and a refractive index difference betweenthe rubber and the matrix resin was 0.030.

Comparative Example 6

Preparation processes were performed in the same manner as in Example 1,except that 40 parts by weight of the graft copolymer powder and 60parts by weight of the matrix resin were used when preparing athermoplastic resin.

The BA content in the resin was 17.2%, a BA coverage value was 77.5%,and the elution amount of BA in a resin sol was 0.74%

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.017, and a refractive index difference betweenthe rubber and the matrix resin was 0.030.

Comparative Example 7

Preparation processes were performed in the same manner as inComparative Example 1, except that 85 parts by weight of the graftcopolymer powder and 15 parts by weight of the matrix resin were usedwhen preparing a thermoplastic resin.

The BA content in the resin was 51.0%, a BA coverage value was 38.0%,and the elution amount of BA in a resin sol was 0%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.022, and a refractive index difference betweenthe rubber and the matrix resin was 0.030.

Comparative Example 8

Preparation processes were performed in the same manner as inComparative Example 1, except that 38 parts by weight of methylmethacrylate and 2 parts by weight of butyl acrylate were used whenpreparing a shell, and 85 parts by weight of the graft copolymer powderand 15 parts by weight of the matrix resin were used when preparing athermoplastic resin.

A grafting degree of the obtained graft copolymer was 35.0%, and theweight-average molecular weight of the shell was 98,000.

The BA content in the resin was 52.7%, a BA coverage value was 32.7%,and the elution amount of BA in a resin sol was 2.59%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.022, and a refractive index difference betweenthe rubber and the matrix resin was 0.030.

Comparative Example 9

Preparation processes were performed in the same manner as in Example 1,except that 0.7 parts by weight of sodium dodecyl sulfate, 3.75 parts byweight of butyl acrylate, and 1.25 parts by weight of styrene were usedwhen preparing a rubber seed, 26.25 parts by weight of butyl acrylateand 8.75 parts by weight of styrene were used to prepare a rubber core,and 47 parts by weight of styrene and 13 parts by weight ofacrylonitrile were used when preparing a shell.

The average particle size of the obtained rubber polymer was 80 nm, agrafting degree of the graft copolymer was 107.0%, and theweight-average molecular weight of the shell was 98,000.

The BA content in the resin was 21.0%, the glass transition temperatureof the rubber was −21° C., a BA coverage value was 176.0%, and theelution amount of BA in a resin sol was 0%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.021, and a refractive index difference betweenthe rubber and the matrix resin was 0.002.

Comparative Example 10

Preparation processes were performed in the same manner as in Example 1,except that 30 parts by weight of a styrene-acrylonitrile resin (S85RFmanufactured by LG Chem) as a matrix resin were used when preparing athermoplastic resin.

A BA coverage value was 77.5%, and the elution amount of BA in a resinsol was 1.89%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.064, and a refractive index difference betweenthe rubber and the matrix resin was 0.107.

Comparative Example 11

Preparation processes were performed in the same manner as in Example 1,except that 30 parts by weight of a styrene-acrylonitrile-methylmethacrylate copolymer (XT500 manufactured by LG Chem) as a matrix resinwere used when preparing a thermoplastic resin.

A BA coverage value was 77.5%, and the elution amount of BA in a resinsol was 1.89%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.031, and a refractive index difference betweenthe rubber and the matrix resin was 0.054.

Comparative Example 12

A graft copolymer was prepared in the same manner as in Example 1,except that 4.25 parts by weight of butyl acrylate and 0.75 parts byweight of methyl methacrylate were used when preparing a rubber seed, 34parts by weight of butyl acrylate and 6 parts by weight of methylmethacrylate were used when preparing a rubber core, and 52.25 parts byweight of methyl methacrylate and 2.75 parts by weight of butyl acrylatewere used when preparing a copolymer shell.

A grafting degree of the obtained graft copolymer was 103%, and theweight-average molecular weight of the shell was 61,000.

A thermoplastic resin was prepared in the same manner as in Example 1,except that the prepared graft copolymer was used in an amount of 50parts by weight, and 50 parts by weight of analphamethylstyrene-styrene-acrylonitrile copolymer (S99UH manufacturedby LG Chem) were used as a matrix resin.

The BA content in the resin was 20.5%, the glass transition temperatureof the rubber was −30° C., a BA coverage value was 125.2%, and theelution amount of BA in a resin sol was 0.4%

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.087, and a refractive index difference betweenthe rubber and the matrix resin was 0.106.

Comparative Example 13

Preparation processes were performed in the same manner as in Example 1,except that 45.6 parts by weight of methyl methacrylate and 14.4 partsby weight of butyl acrylate were used when preparing a shell.

A grafting degree of the obtained graft copolymer was 62%, and theweight-average molecular weight of the shell was 118,000.

The BA content in the resin was 38.1%, a BA coverage value was 41.0%,and the elution amount of BA in a resin sol was 10.82%.

A refractive index difference between the sol and the gel of thethermoplastic resin was 0.018, and a refractive index difference betweenthe rubber and the matrix resin was 0.030.

[Test Examples]

The physical properties of the specimens and films prepared in Examples1 to 12 and Comparative Examples 1 to 13 were measured according to thefollowing methods, and the results are shown in Tables 1 and 2 below.

-   -   DLS average particle diameter: 0.1 g of the prepared rubber        latex (solids content: 35 to 50% by weight) was diluted with 100        g of deionized water to prepare a sample, the particle diameter        of the sample was measured at 23° C. by dynamic light scattering        under an intensity value of 300 kHz in an intensity-weighted        Gaussian analysis mode using a particle size analyzer (Nicomp        CW380, PPS Co.), and the average value of hydrodynamic diameters        obtained from a scattering intensity distribution was obtained        as a DLS average particle diameter.    -   Grafting degree (%): 30 g of acetone was added to 0.5 g of dry        powder of a graft polymer, agitation was performed at 210 rpm at        room temperature (23° C.) for 12 hours using a shaker (SKC-6075,        Lab Companion Co.), centrifugation was performed at 18,000 rpm        at 0° C. for 3 hours using a centrifuge (Supra R30, Hanil        Science Co.) to separate only insoluble matter that was not        dissolved in acetone, and the separated insoluble matter was        dried in a forced circulation manner at 85° C. for 12 hours        using a forced convection oven (OF-12GW, Lab Companion Co.).        Then, the weight of the dried insoluble matter was measured, and        grafting degree was calculated by Equation 3 below.

Grafting degree (%)=[Weight (g) of grafted monomers/Weight (g) ofrubber]×100  [Equation 3]

In Equation 3, the weight of grafted monomers is a value obtained bysubtracting the weight (g) of rubber from the weight of insoluble matter(gel) obtained by dissolving a graft copolymer in acetone and performingcentrifugation, and the weight (g) of rubber is the amount (parts byweight) of rubber components theoretically included in the graftcopolymer powder. Here, the parts by weight of the rubber means thetotal sum of parts by weights of unit components fed when preparing arubber seed and a core.

-   -   Weight average molecular weight (g/mol) of shell: A portion        (sol) dissolved in acetone obtained when measuring the grafting        degree was dissolved in a THF solution, and then the weight        average molecular weight of a shell was obtained as a relative        value to a polystyrene (PS) standard specimen using a GPC.        Specific measurement conditions are as follows.    -   Solvent: tetrahydrofuran (THF)    -   Column temperature: 40° C.    -   Flow rate: 0.3 mL/min    -   Sample concentration: 20 mg/mL    -   Injection amount: 5 μl    -   Column model: 1× PLgel 10 μm MiniMix-B (250×4.6 mm)+1× PLgel 10        μm MiniMix-B (250×4.6 mm)+1× PLgel 10 μm MiniMix-B Guard (50×4.6        mm)    -   Equipment name: Agilent 1200 series system    -   Refractive index detector: Agilent G1362 RID    -   RI temperature: 35° C.    -   Data processing: Agilent ChemStation S/W    -   Test method: Measuring according to OECD TG 118    -   BA content (% by weight): BA content was quantitatively measured        by ¹H NMR analysis or FT-IR analysis. Specific measurement        conditions are as follows.

¹H NMR

-   -   Equipment name: Bruker 600 MHz NMR (AVANCE III HD) CPP BB (1H        19F tunable and broadband, with z-gradient)

Prodigy Probe

-   -   Measurement conditions: ¹H NMR (zg30):ns=32, d1=5 s, TCE-d2, at        room temp.

FT-IR

-   -   Equipment name: Agilent Cary 660    -   Measurement conditions: ATR mode    -   Gel content: 30 g of acetone was added to 0.5 g of dry powder of        the prepared thermoplastic resin, agitation was performed at 210        rpm at room temperature for 12 hours using a shaker (SKC-6075,        Lab Companion Co.), centrifugation was performed at 18,000 rpm        at 0° C. for 3 hours using a centrifuge (Supra R30, Hanil        Science Co.) to separate only insoluble matter that was not        dissolved in acetone, and the separated insoluble matter was        dried in a forced circulation manner at 85° C. for 12 hours        using a forced convection oven (OF-12GW, Lab Companion Co.).        Then, the weight of the dried insoluble matter was measured, and        gel content was calculated by Equation 2 below.

Gel content (%)=[Weight of insoluble matter (gel)/Weight ofsample]×100  [Equation 2]

-   -   Butyl acrylate (BA) coverage (%): Butyl acrylate coverage was        calculated by Equation 1 below.

X (%)={(G−Y)/Y}×100  [Equation 1]

In Equation 1, G represents the total gel content (%) of thethermoplastic resin, and Y represents the content (% by weight) of butylacrylate in the gel. Here, the content (% by weight) of butyl acrylatein the gel was quantitatively measured using an ¹H NMR analyzer orFT-IR.

-   -   Elution amount of butyl acrylate (% by weight): 30 g of acetone        was added to 0.5 g of dry powder of a thermoplastic resin,        agitation was performed at 210 rpm at room temperature for 12        hours using a shaker (SKC-6075, Lab Companion Co.),        centrifugation was performed at 18,000 rpm at 0° C. for 3 hours        using a centrifuge (Supra R30, Hanil Science Co.) to obtain an        acetone solution from which insoluble matter was separated, and        the obtained acetone solution was dried in a forced circulation        manner at 85° C. for 12 hours using a forced convection oven        (OF-12GW, Lab Companion Co.) to obtain a resin sol. Then, ¹NMR        analysis or FT-IR analysis was performed on the resin sol to        quantitatively determine the elution amount of butyl acrylate.    -   Refractive index of rubber: The prepared rubber core was dried        (OF-12GW manufactured by Lab companion) in a forced circulation        method at 90° C. for 24 hr, and then the refractive index        thereof was measured at 25° C. using an Abbe refractometer in        accordance with ASTM D542.    -   Refractive index of matrix resin: A matrix resin was        press-processed at 190° C., and then the refractive index        thereof was measured at 25° C. using an Abbe refractometer in        accordance with ASTM D542.    -   Refractive index of sol and gel: The refractive indexes of each        of the gel obtained by the gel content measurement method and        the sol obtained by the alkyl acrylate elution amount        measurement method was measured at 25° C. using the Abbe        refractometer according to ASTM D542, to obtain a refractive        index difference (ARI).    -   Glass transition temperature: Measured at a temperature increase        rate of 10° C./min using TA Instruments Q100 DSC in accordance        with ASTM D 3418.    -   Impact strength (¼″; kgf·cm/cm): Impact strength was measured at        a temperature of 23° C. according to ASTM D256.    -   Melt index (MI): A melt index was measured at a temperature of        220° C. under a load of 10 kg according to ASTM D1238.        Specifically, a specimen was heated to 220° C. using a melt        indexer (GOETTFERT Co.), the specimen was placed in the cylinder        of the melt indexer, and a load of 10 kg was applied with a        piston. At this time, the weight (g) of a resin melted and        flowing out for 10 minutes was measured, and a melt index was        calculated based on the measured value.

Weather resistance (ΔE): The weather resistance of a specimenmanufactured by adding 1 part by weight of a black colorant to 100 partsby weight of the thermoplastic resin was measured for 6,000 hours underSAE J2527 condition using an accelerated weather resistance testapparatus (weather-o-meter, Ci4000 manufactured by ATLAS, xenon arclamp, Quartz (inner)/S.Boro (outer) filter, irradiance 0.55 W/m² at 340nm), and then evaluated as AE calculated according to Equation 5 below.AE below is an arithmetic mean value of Hunter Lab (L, a, b) valuesmeasured before and after the accelerated weather resistance test. As ΔEis close to 0, weather resistance is superior.

ΔE=√{(L−L′)²+(a−a′)²+(b−b′)²}(√:radical symbol)

-   -   Surface gloss (%): Surface gloss was measured at an incidence        angle of 60° at a temperature of 23° C. using a gloss meter        (VG7000, NIPPON DENSHOKU Co.) according to ASTM D528.    -   Transparency (haze): A film extruded to a thickness of 0.15 mm        and an injection specimen having a thickness of 3 mm were        prepared. The haze value of each of the film and the injection        specimen was measured according to ASTM D-1003 at 23° C. using a        haze meter (model name: HM-150) manufactured by MURAKAMI Co.    -   Whitening: When the prepared film was bent at 180° in the        longitudinal direction (MD) and the transverse direction (TD),        whether whitening occurred was determined by visual observation        (bending-caused whitening).

In addition, a film having a thickness of 0.15 mm and a width and lengthof 100 mm×100 mm was prepared. Then, a weight having a weight of 1 kg(Cat No. 1249, Falling Weight 1 kg) was vertically dropped onto the filmfrom a height of 100 mm at a temperature of 23° C. using a Gardnerimpact tester (Impact Tester 5545, BYK Gardner Co.), haze values beforeand after impact were measured for the middle portion of the filmimpacted by the weight according to ASTM D1003-95, and a difference inhaze values was calculated by Equation 6 below (dropping-causedwhitening).

Difference in haze values=Haze value after dropping−Haze value beforedropping  [Equation 6]

Referring to Tables 1 and 2, in the case of bending-caused whitening,when whitening occurs, it is marked as “O”. When whitening does notoccur (non-whitening), it was marked as “X”. In the case ofdropping-caused whitening, the haze difference values calculated byEquation 6 are shown.

In this case, haze was measured at a temperature of 23° C. using a hazemeter (model name: HM-150, MURAKAMI Co.)

according to ASTM D1003-95.

TABLE 1 BA content in Refractive index thermoplastic difference resin (%by BA between sol Classification weight) coverage (%) and gel Example 130.1 77.5 0.016 Example 2 23.5 116.0 0.013 Example 3 36.8 57.1 0.019Example 4 30.1 72.2 0.017 Example 5 30.1 80.9 0.016 Example 6 30.1 83.60.016 Example 7 28.7 97.3 0.015 Example 8 25.9 125.2 0.013 Example 921.2 217.0 0.009 Example 10 32.2 67.4 0.017 Example 11 36.4 52.8 0.017Example 12 33.5 116.0 0.012 Comparative 42.0 38.0 0.022 Example 1Comparative 17.5 100.0 0.015 Example 2 Comparative 35.0 98.0 0.015Example 3 Comparative 19.6 214.3 0.010 Example 4 Comparative 38.5 38.60.018 Example 5 Comparative 17.2 77.5 0.017 Example 6 Comparative 51.038.0 0.022 Example 7 Comparative 52.7 32.7 0.022 Example 8 Comparative21.0 176.0 0.021 Example 9 Comparative 30.1 77.5 0.064 Example 10Comparative 30.1 77.5 0.031 Example 11 Comparative 20.5 125.2 0.087Example 12 Comparative 38.1 41.0 0.018 Example 13

TABLE 2 Weather Melt index Impact strength Film resistance TransparencyWhitening Classification [g/10 min] [kg · cm/cm] gloss ΔE 0.15 mm 3 mmTD MD Dropping Example 1 7.6 5.3 130 0.8 0.8 2.1 X X 2.5 Example 2 9.34.9 134 1.5 0.6 1.7 X X 1.9 Example 3 5.8 5.8 127 0.7 1.0 2.5 X X 3.5Example 4 9.5 4.0 131 0.5 0.7 2.0 X X 1.6 Example 5 7.2 5.7 125 2.0 0.82.2 X X 2.7 Example 6 6.5 6.4 123 2.6 0.9 2.5 X X 2.9 Example 7 8.5 4.9132 0.7 0.6 1.7 X X 2.3 Example 8 12.0 4.5 133 0.5 0.4 1.2 X X 2.0Example 9 14.9 4.2 138 0.4 0.3 0.9 X X 1.9 Example 10 7.3 5.3 128 1.50.8 1.9 X X 2.1 Example 11 6.6 5.8 123 1.8 0.7 1.7 X X 1.3 Example 127.3 7.0 126 1.8 0.8 1.9 X X 1.5 Comparative 2.4 6.8 90 2.4 4.8 5.7 ◯ ◯76.3 Example 1 Comparative 8.3 2.0 122 1.2 0.7 1.9 ◯ ◯ 43.9 Example 2Comparative 4.6 6.9 96 3.9 2.6 6.1 ◯ ◯ 38.0 Example 3 Comparative 16.21.5 140 1.7 0.6 1.7 X X 28.3 Example 4 Comparative 4.1 6.2 98 1.9 1.02.1 ◯ ◯ 22.5 Example 5 Comparative 10.3 2.1 123 2.2 0.9 2.4 ◯ ◯ 39.8Example 6 Comparative 1.7 8.3 90 3.8 4.1 5.5 ◯ ◯ 70.7 Example 7Comparative 1.3 8.7 86 4.0 3.2 4.9 ◯ ◯ 50.5 Example 8 Comparative 11.24.3 128 3.8 2.3 4.5 X X 2.1 Example 9 Comparative 10.5 5.1 123 2.1 20.481.7 X X 2.6 Example 10 Comparative 6.6 5.3 125 1.5 2.3 6.3 X X 2.8Example 11 Comparative 6.1 4.9 107 1.7 29.2 98.1 X X 3.9 Example 12Comparative 4.8 6.4 102 1.8 1.0 2.2 ◯ ◯ 19.7 Example 13

Referring to Tables 1 and 2, it can be confirmed that the thermoplasticresins (Examples 1 to 12) according to the present invention exhibitexcellent transparency, gloss and weather resistance while appropriatelymaintaining the balance between a melt index and impact strength and,specifically, do not exhibit bending-caused whitening and exhibit a hazedifference of 10 or less before and after dropping impact, whichindicates excellent non-whitening properties. On the other hand, it canbe confirmed that, in the case of the thermoplastic resins (ComparativeExamples 1 to 13) outside the scope of the present invention, thebalance between a melt index and impact strength is decreased, andtransparency, gloss, and weather resistance are generally decreased orwhitening occurs when bent, and a haze difference before and afterdropping impact exceeds 10, which indicates that the property balanceamong transparency, gloss, weather resistance, and non-whiteningproperties is very poor.

FIG. 1 includes images taken after bending, in the Md and Td directions,films manufactured in an example (left image) and a comparative example(right image) to check whether whitening occurs. As shown in FIG. 1, inthe case of the example according to the present invention, whiteningdoes not occur at the bent portion, indicating that the exampleaccording to the present invention has non-whitening properties.However, in the case of the comparative example outside the scope of thepresent invention, whitening occurs clearly at the bent portion.

In addition, FIG. 2 includes images taken after hitting, using a Gardnerimpact tester, films manufactured in an example (left image) and acomparative example (right image) to check whether whitening occurs. Asshown in FIG. 2, similar to FIG. 1, whitening does not occur at the hitportion, indicating that the example according to the present inventionhas non-whitening properties. However, in the case of the comparativeexample outside the scope of the present invention, whitening occursclearly at the hit portion.

1. A thermoplastic resin, comprising: an alkyl acrylate-alkylmethacrylate graft copolymer (A), or the copolymer (A) and a matrixresin (B) comprising one or more selected from the group consisting ofan alkyl methacrylate polymer and an alkyl methacrylate-alkyl acrylatecopolymer, wherein a transparency (haze value), measured according toASTM D-1003 under a condition of 0.15 mm thickness, is 2 or less, and atransparency measured under a condition of 3 mm thickness is 4 or less,a total content of the alkyl acrylate is from 20 to 50% by weight, and abutyl acrylate coverage value (X) as calculated by Equation 1 below is50 or more:X={(G−Y)/Y}×100,  [Equation 1] wherein G represents a total gel content(%) of the thermoplastic resin, and Y represents a content (% by weight)of butyl acrylate in the gel of the thermoplastic resin.
 2. Thethermoplastic resin according to claim 1, wherein a refractive indexdifference (according to ASTM D542) between a sol and a gel of thethermoplastic resin under a condition of using acetone is 0.02 or less.3. The thermoplastic resin according to claim 1, wherein the copolymer(A) is present in an amount of from 50 to 100% by weight, and the matrixresin (B) is present in an amount of from 0 to 50% by weight.
 4. Thethermoplastic resin according to claim 1, wherein, when thethermoplastic resin is eluted using acetone, an elution amount of thebutyl acrylate is 0.01% by weight or more.
 5. The thermoplastic resinaccording to claim 1, wherein the copolymer (A) comprises from 25 to 50%by weight of an alkyl acrylate rubber (a-1) having a DLS averageparticle diameter of from 40 to 120 nm or a TEM average particlediameter of from 25 to 100 nm; and from 50 to 75% by weight of an alkylacrylate-alkyl methacrylate copolymer (a-2) based on 100% by weight intotal of the copolymer (A).
 6. The thermoplastic resin according toclaim 5, wherein the copolymer (A) has a grafting degree of from 60 to200%, and the copolymer (a-2) has a weight-average molecular weight offrom 40,000 to 120,000 g/mol.
 7. The thermoplastic resin according toclaim 5, wherein the thermoplastic resin, the rubber (a-1), or both thethermoplastic resin and the rubber (a-1) has a glass transitiontemperature of from −50 to −20° C.
 8. The thermoplastic resin accordingto claim 5, wherein the rubber (a-1) further comprises alkylmethacrylate.
 9. The thermoplastic resin according to claim 8, whereinthe alkyl methacrylate is present in an amount of from 0.1 to 25% byweight based on 100% by weight in total of the rubber (a-1).
 10. Thethermoplastic resin according to claim 5, wherein the copolymer (a-2)comprises from 80 to 99.9% by weight of the alkyl methacrylate and from0.1 to 20% by weight of the alkyl acrylate based on 100% by weight intotal of the copolymer (a-2).
 11. The thermoplastic resin according toclaim 5, wherein a refractive index difference (according to ASTM D542)between the rubber (a-1) and the matrix resin (B) is 0.02 or more. 12.The thermoplastic resin according to claim 1, wherein, when thethermoplastic resin is extruded to obtain a film having a thickness of0.15 mm, and a weight having a weight of 1 kg is vertically dropped ontothe film from a height of 100 mm at a temperature of 23° C. using aGardner impact tester, a difference in transparencies measured beforeand after impact according to ASTM D1003-95 for an area impacted by theweight is 10 or less.
 13. A method of preparing a thermoplastic resin,the method comprising: kneading and extruding an alkyl acrylate-alkylmethacrylate graft copolymer (A), or the copolymer (A) and a matrixresin (B) comprising one or more selected from the group consisting ofan alkyl methacrylate polymer and an alkyl methacrylate-alkyl acrylatecopolymer, wherein a transparency (haze value), measured according toASTM D-1003 under a condition of 0.15 mm thickness, of the thermoplasticresin is 2 or less, and a transparency measured under a condition of 3mm thickness is 4 or less, a total content of the alkyl acrylate in thethermoplastic resin is from 20 to 50% by weight, and a butyl acrylatecoverage value (X), as calculated by Equation 1 below, of thethermoplastic resin is 50 or more:X={(G−Y)/Y}×100,  [Equation 1] wherein G represents a total gel content(%) of the thermoplastic resin, and Y represents a content (% by weight)of butyl acrylate in the gel of the thermoplastic resin.
 14. The methodaccording to claim 13, wherein the graft copolymer (A) is prepared byemulsion polymerization of 100 parts by weight in total of a monomermixture comprising from 25 to 50 parts by weight of alkyl acrylaterubber having a DLS average particle diameter of from 40 to 120 nm or aTEM average particle diameter of from 25 to 100 nm; and 50 to 75 partsby weight of an alkyl acrylate compound and an alkyl methacrylatecompound.
 15. A molded article, comprising the thermoplastic resinaccording to claim
 1. 16. The molded article according to claim 15,wherein the molded article is a finishing material.
 17. The methodaccording to claim 13, wherein the copolymer (A) comprises from 25 to50% by weight of an alkyl acrylate rubber (a-1) having a DLS averageparticle diameter of from 40 to 120 nm or a TEM average particlediameter of from 25 to 100 nm; and from 50 to 75% by weight of an alkylacrylate-alkyl methacrylate copolymer (a-2) based on 100% by weight intotal of the copolymer (A).